http://septentrio.uit.no/index.php/NAMMCOSP/issue/feedNAMMCO Scientific Publications2018-02-23T09:31:28+01:00Jill Prewittjill.prewitt@nammco.noOpen Journal Systems<p>The NAMMCO Scientific Publications series makes available in published, peer-reviewed form, scientific papers that have contributed to the work carried out by the NAMMCO Scientific Committee.</p>http://septentrio.uit.no/index.php/NAMMCOSP/article/view/2609A study on the improvement of age estimation in common minke whales using the method of gelatinized extraction of earplug2016-02-03T09:43:20+01:00Hikari Maedahikari.maeda@gmail.comTadafumi Kawamotokawamoto-t@tsurumi-u.ac.jpHidehiro Katokatohide@kaiyodai.ac.jp<p class="MsoNormal" style="text-align: justify; text-justify: inter-ideograph;"><span style="font-family: &quot;Times New Roman&quot;,&quot;serif&quot;;">We attempted to settle the potential problems of bias caused by too soft earplugs and poor formation of the growth layers in age readings of common minke whales. Thus, we examined the feasibility of a new technique of incorporating gelatin in order to collect earplugs for age assessment. Frozen sectioning and histology of the earplug core were also used as methods to improve age estimation. Earplugs were collected by filling the space in the external auditory meatus with gelatin, hardening the gelatin, earplug and its fragments, by spraying with cooling gas, and removing the earplug embedded in gelatin. In 174 trials with common minke whales in the Western North Pacific of coastal waters of Japan in 2007&ndash;2009, it was revealed that embedding earplugs with gelatin minimized breakage and protected the neonatal line (NL). This method was particularly effective in younger animals. As a result, the readability was improved. We also examined the histological sections, which were sliced using the Kawamoto specialized frozen sectioning technique, and stained them separately with toluidine blue, haematoxylin and eosin, Sudan III, Sudan VII, and alizarin red S to display a clearer core surface image of the growth layers. The histological sections stained with alizarin red S provided the clearest images, in which we could easily identify both dark and pale laminations. This suggested a close relationship with the seasonal changes in calcium intake from feeding. Earlier age estimation methods focused on fat content in the growth layers; however, we found potential for an improvement in the readability of unclear growth layers when focusing on calcium.</span></p>2013-08-21T00:00:00+02:00Copyright (c) 2013 Hikari Maeda, Tadafumi Kawamoto, Hidehiro Katohttp://septentrio.uit.no/index.php/NAMMCOSP/article/view/2616Use of Micro-Computed Tomography for Dental Studies in Modern and Fossil Odontocetes: Potential Applications and Limitations2016-02-03T09:43:20+01:00Carolina Lochcarolina.loch@otago.ac.nzDonald R Schwassdonald.schwass@otago.ac.nzJules A Kieserjules.kieser@otago.ac.nzR Ewan Fordyceewan.fordyce@otago.ac.nz<p class="MsoNormal" style="margin-top: 12.0pt; text-align: justify;"><span lang="EN-US">Teeth are important elements in studies of modern and fossil Cetacea (whales, dolphins), providing information on feeding habits, estimations of age and phylogenetic relationships. The growth layer groups (GLGs) recorded in dentine have demonstrated application for aging studies, but also have the potential to elucidate life history phenomena such as metabolic or physiologic events. Micro-Computed Tomography (Micro-CT) is a non-invasive and non-destructive technique that allows 3-dimensional study of mineralized tissues, such as human teeth, and their physical properties. Teeth from extant dolphins (Cetacea: Odontoceti) and some fossil odontocetes were scanned in a Skyscan 1172 Micro-CT desktop system. X-rays were generated at 100 kV and 100 &micro;A for extant samples, and at 80kV and 124 &micro;A for fossils. 0.5 mm thick aluminum and copper filters were used in the beam. Reconstructed images were informative for most extant species, showing a good resolution of the enamel layer, dentine and pulp cavity. Greyscale changes in the dentinal layers were not resolved enough to show GLGs. Visualization of the </span><span lang="EN-AU">internal structure in fossil cetacean teeth depended on the degree of diagenetic alteration in the specimen; undifferentiated enamel and dentine regions probably reflect secondary mineralization. However, internal details were finely resolved for one fossil specimen, </span><span lang="EN-US">showing the enamel, internal layers of dentine and the pulp cavity. </span><span lang="EN-AU">Micro-CT has been proven to be a useful tool for resolving the internal morphology of fossil and extant teeth of cetaceans before they are sectioned for other morphological analyses; however some methodological refinements are still necessary to allow better resolution of dentine for potential application in non-destructive age determination studies.&nbsp;</span></p>2013-10-08T10:46:51+02:00Copyright (c) 2013 Carolina Loch, Donald R Schwass, Jules A Kieser, R Ewan Fordycehttp://septentrio.uit.no/index.php/NAMMCOSP/article/view/2987Bomb dating, age validation and quality control of age determinations of monodontids and other marine mammals2016-02-03T09:43:20+01:00Steven E Campanajill.prewitt@nammco.noRobert EA Stewartjill.prewitt@nammco.noMethods for confirming the accuracy of age determination methods are reasonably well established in fishes, but the millions of routine age determinations which take place every year require their own quality control protocols. In contrast, methods for ensuring accuracy in age determination of monodontids and other marine mammals are still being developed. Here we review the basis and application of bomb radiocarbon to marine mammal age validation, highlighting its value for providing unambiguous estimates of age for belugas and other long-lived animals which form growth bands. Bomb radiocarbon is particularly useful for marine mammals, given that the age of an individual animal can be determined to within ±1-3 years, as long as it was alive during the 1960s. However, ongoing age determinations require careful monitoring to ensure that age interpretations remain consistent across ages and through time. Quality control protocols using reference collections of ageing material, in conjunction with age bias plots and measures of precision, are capable of detecting virtually all of the systematic ageing errors that often occur once age determinations of an animal become routine.2014-05-11T20:58:47+02:00Copyright (c) 2014 Steven E Campana, Robert EA Stewarthttp://septentrio.uit.no/index.php/NAMMCOSP/article/view/3017Deposition of growth layer groups in dentine tissue of captive common dolphins <i>Delphinus delphis</i>2016-02-03T09:43:20+01:00Sinéad Murphyjill.prewitt@nammco.noMatthew Perrottjill.prewitt@nammco.noJill McVeejill.prewitt@nammco.noFiona L Readjill.prewitt@nammco.noKarin A Stockinjill.prewitt@nammco.no<p>Knowledge of age structure and longevity (maximum age) are essential for modelling marine mammal population dynamics. Estimation of age in common dolphins (<em>Delphinus</em> spp.) is primarily based on counting Growth Layer Groups (GLGs) in the dentine of thin, decalcified and stained sections of teeth. An annual incremental deposition rate was validated for <em>Delphinus </em>spp. 30-years ago through the use of tetracycline. However, it is not known if the pulp cavity becomes occluded in older individuals or GLGs continue to be deposited in dentine tissue. To investigate the deposition of GLGs in dentine tissue, teeth samples were obtained during the necropsies of two short-beaked common dolphins (<em>Delphinus delphis</em>) that were held in captivity for 31 and 33 years in New Zealand. Individuals were captured together in Hawkes Bay, North Island, New Zealand and classified as juveniles based on physical appearance. Teeth were processed in two ageing laboratories, using four different bone decalcifiers, two sectioning techniques incorporating the use of both a freezing microtome (-20<sup>°</sup>C) and paraffin microtome, and two different stains. An age was estimated for one of the dolphins, in line with that proposed based on estimated age at capture and period in captivity. However, a hypomineralised area was observed in the dentine tissue close to the pulp cavity of the second individual, preventing estimation of maximum age. The presence and structure of this anomaly is explored further within the study. </p>2014-07-18T13:20:50+02:00Copyright (c) 2014 Sinéad Murphy, Matthew Perrott, Jill McVee, Fiona L Read, Karin A Stockinhttp://septentrio.uit.no/index.php/NAMMCOSP/article/view/3195The biology behind the counts: tooth development related to age estimation in beluga (<i>Delphinapterus leucas</i>)2016-02-03T09:43:20+01:00Barbara E Stewartjill.prewitt@nammco.noRobert EA Stewartjill.prewitt@nammco.no<p>The widely accepted method of determining ages of beluga is to count dentine growth layer groups (GLGs) in median, longitudinal sections of a tooth. It is essential to understand how these growth layers form and to consider developmental factors that can confound their enumeration to be able to provide meaningful age estimates. Here we provide information on, and illustrate, the developmental biology of beluga teeth as it relates to interpreting GLGs. Key factors are: evaluating the presence and occlusal wear of fetal dentine; interpreting early-formed diagnostic features such as the neonatal line; assessing the last-formed growth layer adjacent to the pulp cavity; identifying the presence of nodes at the dentine-cementum interface to assist in counting GLGs; and recognizing pulp stones and accessory lines in the dentine which may hinder the age estimate process.</p>2014-11-26T10:10:41+01:00Copyright (c) 2014 Barbara E Stewart, Robert EA Stewarthttp://septentrio.uit.no/index.php/NAMMCOSP/article/view/3196Validation of dentine deposition rates in beluga whales by interspecies cross dating of temporal δ13C trends in teeth2016-02-03T09:43:20+01:00Cory JD Matthewsjill.prewitt@nammco.noSteven H Fergusonjill.prewitt@nammco.no<p>Isotopic time series from sequentially sampled growth layer groups (GLGs) in marine mammal teeth can be combined to build chronologies allowing assessment of isotopic variation in marine ecosystems. Synchronous recording of baseline isotopic variation across dentinal GLGs of species with temporal and spatial overlap in foraging offers a unique opportunity for validation of marine mammal age estimation procedures through calibration of GLG deposition rates in one species against another whose GLG deposition has been independently determined. In this study, we compare trends in stable carbon isotope ratios (d<sup>13</sup>C) across dentinal GLGs of three eastern Canadian Arctic (ECA) beluga (<em>Delphinapterus leucas</em>) populations through the 1960s-2000s with a d<sup>13</sup>C time series measured across dentinal GLGs of ECA/Northwest Atlantic killer whales (<em>Orcinus orca</em>) from 1944-1999. We use confirmed annual GLG deposition in killer whales as a means to assess beluga GLG deposition, and show linear d<sup>13</sup>C declines across chronologies of both species were statistically indistinguishable when based on annual GLG deposition in beluga whales, but differed when based on biannual deposition. We suggest d<sup>13</sup>C declines reflect the oceanic <sup>13</sup>C Suess effect, and provide additional support for annual GLG deposition in beluga whales by comparing rates of d<sup>13</sup>C declines across beluga GLGs with published annual d<sup>13</sup>C declines attributed to the oceanic <sup>13</sup>C Suess effect in the North Atlantic.</p>2014-11-26T13:25:34+01:00Copyright (c) 2014 Cory JD Matthews, Steven H Fergusonhttp://septentrio.uit.no/index.php/NAMMCOSP/article/view/3194Utility of telomere length measurements for age determination of humpback whales2016-02-03T09:43:20+01:00Morten Tange Olsenjill.prewitt@nammco.noJooke Robbinsjill.prewitt@nammco.noMartine Bérubéjill.prewitt@nammco.noMary Beth Rewjill.prewitt@nammco.noPer J Palsbølljill.prewitt@nammco.no<p>This study examines the applicability of telomere length measurements by quantitative PCR as a tool for minimally invasive age determination of free-ranging cetaceans. We analysed telomere length in skin samples from 28 North Atlantic humpback whales (<em>Megaptera novaeangliae</em>), ranging from 0 to 26 years of age. The results suggested a significant correlation between telomere length and age in humpback whales. However, telomere length was highly variable among individuals of similar age, suggesting that telomere length measured by quantitative PCR is an imprecise determinant of age in humpback whales. The observed variation in individual telomere length was found to be a function of both experimental and biological variability, with the latter perhaps reflecting patterns of inheritance, resource allocation trade-offs, and stochasticity of the marine environment.</p>2014-12-05T09:57:53+01:00Copyright (c) 2014 Morten Tange Olsen, Jooke Robbins, Martine Bérubé, Mary Beth Rew, Per J Palsbøllhttp://septentrio.uit.no/index.php/NAMMCOSP/article/view/3268An evaluation of age estimation using teeth from South Asian River dolphins (Platanistidae)2016-02-03T09:43:20+01:00Christina H Lockyerjill.prewitt@nammco.noGill T Braulikjill.prewitt@nammco.no<p>The South Asian river dolphins (<em>Platanista gangetica minor </em>and<em> P. g. gangetica</em>) are endangered, geographically isolated, freshwater cetaceans. Accurate age estimation of individuals is an important aspect of population biology as it is used for calculating parameters such as age at maturity and reproduction, longevity, and growth and survival rates. However this has never been comprehensively studied for this endangered cetacean family. A sample of 41 teeth from 29 skulls stored in museum collections was available. We compared two different aging methods to select the most appropriate. This involved decalcification and freeze-sectioning of teeth at variable thicknesses (10–25 micron), and staining with 1) Toluidine Blue, or 2) Ehrlichs Acid Haematoxylin. Stains were then compared for readability of Growth Layer Groups (GLG). The optimum section was found at 20 micron using Erhlichs Acid Haematoxylin. Both dentinal and cemental GLG were readable and comparable, but cemental GLG were generally easier to interpret because they were better defined. Ages varied from newborn / young of year (with none or only a neonatal line present) to a maximum age of 30 GLG. There is currently no validation available for GLG deposition rate, but it is likely annual because of the extreme seasonal changes in the river habitat. </p>2014-12-23T11:14:56+01:00Copyright (c) 2014 Christina H Lockyer, Gill T Braulikhttp://septentrio.uit.no/index.php/NAMMCOSP/article/view/3786Inter-lab comparison of precision and recommended methods for age estimation of Florida manatee (Trichechus manatus latirostris) using growth layer groups in earbones2016-06-02T19:20:17+02:00Katherine Brilljill.prewitt@nammco.noMiriam Marmonteljill@nammco.noMeghan Bolen-Richardsonjill@nammco.noRobert EA Stewartjill@nammco.no<p>Manatees are routinely aged by counting Growth Layer Groups (GLGs) in periotic bones (earbones). Manatee carcasses recovered in Florida between 1974 and 2010 provided age-estimation material for three readers and formed the base for a retrospective analysis of aging precision (repeatability). All readers were in good agreement (high precision) with the greatest apparent source of variation being the result of earbone remodelling with increasing manatee age. Over the same period, methods of sample preparation and of determining a final age estimate changed. We examined the effects of altering methods on ease of reading GLGs and found no statistical differences. Accurate age estimates are an important component for effective management of the species and for better models of population trends and we summarize the currently recommended methods for estimating manatee ages using earbones. </p>2016-06-01T09:48:27+02:00Copyright (c) 2016 Katherine Brill, Miriam Marmontel, Meghan Bolen-Richardson, Robert EA Stewarthttp://septentrio.uit.no/index.php/NAMMCOSP/article/view/4184Two techniques of age estimation in cetaceans: GLGs in teeth and earplugs, and measuring the AAR rate in eye lens nucleus2017-08-07T10:07:33+02:00Nynne H Nielsenjill.prewitt@nammco.noGísli A. Víkingssonjill@nammco.noSteen H. Hansenjill@nammco.noSusanne Ditlevsenjill@nammco.noMads Peter Heide-Jørgensenjill@nammco.no<p>The ages of three species of cetaceans were estimated by counting the growth layer groups (GLG) and measuring the aspartic acid racemization rate (<em>k</em><sub>Asp</sub>) by what is referred to as the Aspartic Acid Racemization (AAR) technique. Data on <em>k</em><sub>Asp</sub> and the D/L ratio of aspartic acid at birth [(D/L)<sub>0</sub>] in North Atlantic common minke whales (<em>Balaenoptera acutorostrata</em>) are presented along with data on fin whales (<em>B. physalus</em>) and harbour porpoises (<em>Phocoena phocoena</em>) already published by Nielsen <em>et al.</em> (2012). The <em>k</em><sub>Asp</sub> specific for minke whales was 1.40 x 10<sup>-3 </sup>yr<sup>-1</sup> (SE ± 0.00005) and the (D/L)<sub>0</sub> was 0.0194 (SE ± 0.0012). The correlation of GLG age and D/L ratio for all three species was highly significant; however, the correlation coefficient varied greatly (fin whales: R<sup>2</sup> = 0.59, p &lt;0.0001; minke whales: ­R<sup>2</sup>=0.96, P &lt;0.0001; harbour porpoises: ­R<sup>2</sup>=0.36, P &lt;0.0001). Asymptotic body length for all three species was estimated by a von Bertalanffy growth model on both the GLG and AAR techniques, and showed no difference.</p>2017-08-07T09:57:44+02:00Copyright (c) 2017 Nynne H Nielsen, Gísli A. Víkingsson, Steen H. Hansen, Susanne Ditlevsen, Mads Peter Heide-Jørgensenhttp://septentrio.uit.no/index.php/NAMMCOSP/article/view/4400Accuracy of the Aspartic Acid Racemization Technique in Age Estimation of Mammals and the Influence of Body Temperature2018-02-23T09:31:28+01:00Eva Gardejill.prewitt@nammco.noMads F. Bertelsenjill@nammco.noSusanne Ditlevsenjill@nammco.noMads Peter Heide-Jørgensenjill@nammco.noNynne H. Nielsenjill@nammco.noAnne K. Friejill@nammco.noDroplaug Olafsdottirjill@nammco.noUrsula Siebertjill@nammco.noSteen H. Hansenjill@nammco.no<p>The aspartic acid racemization (AAR) technique has been applied for age estimation of humans and other mammals for more than four decades. In this study, eye lenses from 124 animals representing 25 mammalian species were collected and D/L ratios obtained using the AAR technique. The animals were either of known age or had the age estimated by other methods. The purpose of the study was to: a) estimate the accuracy of the AAR technique, and b) examine the effect of body temperature on racemization rates. Samples from four of the 25 species covered the range of ages that is needed to estimate species-specific racemization rates. The sample size from a single species of known age, the pygmy goat (<em>Capra hircus, n </em>= 35), was also large enough to investigate the accuracy of ages obtained using the AAR technique. The 35 goats were divided into three datasets: all goats (n = 35), goats &gt;0.5 yrs old (n = 26) and goats &gt;2 yrs old (n = 19). Leave-one-out analyses were performed on the three sets of data. Normalized root mean squared errors for the group of goats &gt;0.5 yrs old were found to be the smallest. The higher variation in D/L measurements found for young goats &lt;0.5 yrs can probably be explained by a period of continued postnatal growth of the eye lens. Normalized root mean squared errors from the leave-one-out cross-validation analyses based on goats &gt;0.5 yrs old was for three age groups of the goats: 0.934 yrs for young goats &lt;2 yrs (<em>n</em> = 16), 0.102 yrs for adult goats from 2–8 yrs (<em>n</em> = 15) and 0.133 yrs for old goats &gt;8 yrs (<em>n</em> = 4). Thus, the age of an adult or an old animal can be predicted with approximately 10% accuracy, whereas the age of a young animal is difficult to predict. A goat specific racemization rate, as a 2<em>k</em><sub>Asp </sub>value, was estimated to 0.0107 ± 3.8 x 10<sup>-4</sup> SE (<em>n</em> = 26). The 2<em>k</em><sub>Asp </sub>values from 12 species, four estimated in this study and another eight published, were used to examine the effect of core body temperature on the rate of racemization. A positive relationship between AAR and temperature was found (<em>r<sup>2</sup> </em>= 0.321) but results also suggest that other factors besides temperature are involved in the racemization process in living animals. Based on our results we emphasize that non-species-specific racemization rates should be used with care in AAR age estimation studies and that the period of postnatal growth of the eye lens be considered when estimating species-specific D/L<sub>0</sub> values and ages of young individuals.</p>2018-02-23T09:29:48+01:00Copyright (c) 2018 Eva Garde, Mads F. Bertelsen, Susanne Ditlevsen, Mads Peter Heide-Jørgensen, Nynne H. Nielsen, Anne K. Frie, Droplaug Olafsdottir, Ursula Siebert, Steen H. Hansenhttp://septentrio.uit.no/index.php/NAMMCOSP/article/view/3731Report of the workshop on age estimation in beluga: Beaufort, North Carolina, US 5-9 December 20112016-02-04T17:39:56+01:00Christina Lockyerjill.prewitt@nammco.noAleta A. Hohnjill@nammco.noRoderick Hobbsjill@nammco.noRobert EA Stewartjill@nammco.no<p>A workshop convened by C. Lockyer and A. A. Hohn to examine variation among readers in estimating beluga ages was held in Beaufort, North Carolina, US. Terms of Reference for the workshop included the following:</p><p>1. Provide a guide as to acceptable levels of accuracy and precision for age reading that will enable ages to be used in population models.</p><p>2. Conduct an inter-reader/laboratory comparison for calibration and standardization of age readings from GLG counts among all readers/laboratories.</p><p>3. Provide information on validation that will enable GLG counts to be translated to real age.</p><p>4. Produce a manual of guidelines for the preparation and reading of GLGs in beluga teeth.</p><p>Presentations by participants are abstracted here. Then we report on the processes used to compare sections, images, and interpretation, and generate guidelines for best practices in beluga age estimation. A comparative study quantified differences among readers and found that precision of experienced readers was good, higher than reported for other odontocetes. Participants agreed that counting GLGs using well prepared thin sections was preferred because they are simpler to prepare than stained sections and there was more agreement among readers compared to using half sections. Examination of teeth from captive beluga as both untreated sections and stained sections and did not clarify the reading of wild beluga teeth. This Workshop concurred with Workshop 1 (Tampa 26-27 November 2011) that interpreting one GLG as an annual record is irrefutable. Guidelines for best practices were developed.</p>2016-02-03T09:43:00+01:00Copyright (c) 2016 Christina Lockyer, Aleta A. Hohn, Roderick Hobbs, Robert EA Stewarthttp://septentrio.uit.no/index.php/NAMMCOSP/article/view/3743Report of the Workshop on Age Estimation in Monodontids2016-05-31T19:18:42+02:00Aleta A Hohnjill.prewitt@nammco.noChristina Lockyerjill@nammco.noMario Acquaronejill@nammco.no<p>The workshop was a 2-day event organised immediately before the Society for Marine Mammalogy biennial conference in Tampa. NAMMCO funding enabled participation of 4 invited experts and also supported the organization and logistics associated with the workshop. The breadth and depth of the workshop presentations made it clear that most issues concerning monodontid age estimation are not unique. Many researchers investigating many taxa have considered a diversity of methods and tissues to reveal biological records of age. Aside from the biological materials, accuracy and precision of the counts or metric have been considered, as well as their interpretation.</p><p> </p>2016-05-30T09:34:35+02:00Copyright (c) 2016 Aleta A Hohn, Christina Lockyer, Mario Acquarone